The present application claims priority under 35 U.S.C. xc2xa7119 of Swiss Patent Application No.2001 1698/01, filed on Sep. 14, 2001, the disclosure of which is expressly incorporated by reference in its entirety.
1. Field of the Invention
The present invention concerns an apparatus for keeping hot and for transporting dishes, in particular pizzas, from a producer to a consumer using a motor vehicle.
2. Discussion of Background Information
Transport of prepared dishes, and in particular of pizzas, using a motor vehicle such as an automobile or motorcycle, has become general practice, particularly in cities. Rapid transport is expected, and above all, the dishes transported are expected to arrive in prime condition, hot and with all the characteristics of fragrance, taste and crispness they presented at the moment they were produced. In particular pizzas, being the product transported most frequently using motor vehicles, are most susceptible with respect to the fragrance and crispness problem: the increase in humidity softens them and deprives them of their fundamental product characteristics, i.e., mainly their fragrance. Thus humidity control during the transport of the product plays a decisive role in successful transport operations.
Today various proposals are known for solving this problem. For example, the simplest system practically applied is the insertion of the dishes to be transported into thermally insulated bags. This system is a low-cost operation but presents serious disadvantages due to the fast drop in temperature of the product causing a corresponding increase in humidity. The pizza delivered presents itself soggy and at the limit of fitness for consumption. Above all, this system presents severe hygienic problems, as cleaning of the bags is difficult, the bags easily becoming breeding grounds for dangerous bacteria. The same holds true for boxes and containers made from synthetic materials: they present the same disadvantages as the bags, differing in relevant part in that they are
From the patent literature and from practical use technologically more advanced solutions of the problem are known, such as the solutions according to European Patent Publication No. EP-0481352A1 or European Patent Publication No. EP-0575471A1 (the invention also being shown in PCT International Publication No. WO92/16137).
In EP-0481352A1 an apparatus is shown for transporting and for keeping hot dishes in particular pizzas, where the container presents a lower portion and an upper portion, the lower portion being laid out as a functional part containing a fan and a heating device as well as a dehumidifying chamber. The fact that the apparatus requires a dehumidification chamber exemplifies a primary limitation of this system, namely, that the airflow in the chamber of the container is laid out in such a manner that dehumidification of the air with the help of a hygroscopic substance (such as, e.g., bran, which was cited as an example) is required. This solution is further problem-ridden, as its practical application dictates the use of a thermostat as well as of a hygrostat for controlling temperature and humidity of the air. Such arrangements render the layout of the apparatus complex and unsuitable for daily practical use.
EP-0575471A1, an equivalent of PCT-WO92/16137, shows a solution including an 1 apparatus for transporting, also known to be in practical use, namely a dish-heater with a gasoline burner. In the air circulation circuit inside the container, a heat exchanger is arranged in a separate chamber and laid out as a radiator or as an electrical heater or as a gasoline burner. An apparatus of this type is capable of maintaining the temperature inside the container over prolonged time periods, but does not solve the crucial problem of humidity control, and thus the quality of the product transported suffers. Furthermore the apparatuses of such type, of which the type with a gasoline burner is known best, all present a series of further disadvantages, such as elevated operating cost, higher noise level, danger of fire, hygiene problems, etc. Particularly disturbing is the fact that the hot air flow re-circulated inside the container is not filtered and thus carries harmful particles with it, which can be deposited onto the dishes in transport.
All these known systems, in which a heat exchanger receiving its heat energy in any specific manner (e.g., from the cooling system of the motor vehicle as described in EP-0628277A1 or also by analogy to the one shown in GB-2316739A using the exhaust fumes of the vehicle) is arranged in a separate chamber of the container for the actual dishes, are not preoccupied particularly with correct circulation of the hot air in the container nor with correct thermal insulation of the container, being limited to the provision of an insulated box in which shelves supporting the dishes are arranged. The humidity of the air thus cannot be controlled sufficiently and thus the dishes, in particular the pizzas, absorb too much humidity and go limp during transport.
The present invention provides for a device for keeping hot and for transporting dishes comprising a thermally insulated container in which the air circulation is laid out in such a manner that the above mentioned disadvantages of the devices known thus far are eliminated and that a stable temperature (of at least 130xc2x0 C.) and perfect humidity control are ensured in the container, the most stringent hygiene standards being complied with.
Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawings.
The overall layout of the container generally forms as a box or receptacle with walls comprising an air interspace for continually supplying fresh air from the outside into the inner chamber, which then is drained off continually via an exhaust opening provided in the bottom part of the container, and owing to this arrangement the air inside the box can circulate as freely as possiblyxe2x80x94care having been taken that all unnecessary internal obstacles are eliminatedxe2x80x94and constant ideal heating conditions for heating the dishes are obtained.
Of course this mode requires that sufficient heat is available, which implies that the heat exchanger provided must be able to supply the required heat energy. This can be effected using heat exchangers of all types, but the preferred solution is to employ the thermal energy of the exhaust fumes of the engine of the automobile as the heat source, but not in direct relation to dishes as described in the above mentioned GB-23 16739A. Swiss patent application No. 1999 1264/99, dated Jul. 9, 1999, describes a vehicle comprising an oven for dishes heated using the exhaust fumes of the engine of the vehicle.
According to another aspect of the invention, an apparatus is provided for keeping hot and for transporting prepared dishes from a producer to a consumer, using a motor vehicle equipped with a thermally insulated container. The container includes a lower portion supported by the motor vehicle in which a heat exchanger is provided. The container comprises a receptacle having a top, a bottom, a front and a rear, forming an inner chamber wherein the receptacle defines a through passage opening forming an air passage to ambient space. The receptacle further comprises a continuous wall having a double wall portion enclosing a continuous air interspace. This double wall portion defines an air inlet to permit ambient air to be drawn into the air interspace, and, defines an air outlet connected to the inner chamber of the receptacle to permit exhaust to ambient air. To move ambient air into the inner chamber, a blowing fan for directing ambient air into the air inlet is provided whereby the inner chamber is connected with the ambient air and continuous air flow is permitted to circulate through the inner chamber to be exhausted through the through passage opening located in the lower portion.
The receptacle also, of course, includes a door for permitting access to the inner chamber and shelves within the inner chamber for placement of the dishes. The shelves may be perforated or spaced from the receptacle wall within the inner chamber to form an air space, whereby free circulation of air within the inner chamber is maximized.
The door is preferably located at the front of the receptacle where the double wall portion defines the air outlet, thereby being proximate to the door and front, so that air stream vortices are maximized. To increase air intake into the double wall portion, at least two blowing fans may be attached to the continuous wall proximate to the top of the receptacle.
The double wall portion may comprise an external wall and an external top cover and an internal wall and internal top cover wherein the external wall and external top cover are made from wood and the internal wall and internal top cover are made from metal, preferably steel. In lieu of wood, the external wall and external top cover may be made of a material presenting thermal insulating characteristics similar to wood.
The motor vehicle on which the container is provided may include a combustion engine, an exhaust supply tube in communication with the combustion engine for exhausting combustion exhaust fumes, and an exhaust tube, wherein the heat exchanger is interposed between the exhaust supply tube and the exhaust tube. Typically, the through passage opening is located at the bottom of the receptacle and receives the exhaust supply tube and the exhaust tube from the motor vehicle. Thus, the heat exchanger is supplied with thermal energy from the exhaust fumes of the combustion engine of the motor vehicle when in operation. Also, the heat exchanger should comprise components for conducting and radiating heat to the inner chamber from a heat source supplied to the heat exchanger and air-impermeably separated from the inner chamber, thereby preventing the exhaust fumes from reaching the inner chamber, but allowing thermal exchange. Ideally, the heat exchanger is calibrated to maintain an air temperature in the inner chamber above 130xc2x0 C. The container is thermally insulated so that the inner chamber maintains its temperature.
When the motor vehicle is a van with a load carrying compartment, the container may be sized to fit and mounted in such compartment. When the motor vehicle is a car with a trunk, the container is preferably sized to fit and be mounted therein. If the motor vehicle is a motorcycle, the motorcycle may have a luggage rack located behind a driver""s seat for mounting the container. In some cases, the motor vehicle has reinforced points provided as anchoring points for seat belts; in such cases, the container may be secured to such reinforced points.
In many cases, the container may be well suited to these types of motor vehicles having a width ranging from approximately 50 cm to 100 cm, a depth ranging from approximately 40 to 60 cm, and a height ranging from approximately 30 cm to 70 cm. Particularly when dishes to be carried are pizzas, the receptacle ideally comprises a box, including lateral walls having dimensions which approximate a square.
The invention provides an apparatus for keeping hot and for transporting prepared dishes from a producer to a consumer, using a motor vehicle equipped with a container having a lower portion supported by the motor vehicle in which a heat exchanger is provided, wherein the motor vehicle includes a combustion engine, an exhaust supply tube in communication with the combustion engine for exhausting combustion exhaust fumes, an exhaust tube, and wherein the heat exchanger is interposed between the exhaust supply tube and the exhaust tube and thereby is supplied with thermal energy from the exhaust fumes of the combustion engine of the motor vehicle, the apparatus comprising a receptacle having a top, a bottom, a front and a rear, forming an inner chamber, the receptacle defining a through passage opening forming an air passage to ambient space wherein the through passage opening is located at the bottom of the receptacle and receives the exhaust supply tube and the exhaust tube. The receptacle further comprises a continuous wall having a double wall portion enclosing a continuous air interspace, the double wall portion defining an air inlet to permit ambient air to be drawn into the air interspace, and, defining an air outlet connected to the inner chamber proximate to the front, whereby air stream vortices are maximized, and wherein the double wall portion further comprises an external wall and an external top cover and an internal wall and internal top cover. The receptacle has a door for access to the inner chamber and located at the front, and, a perforated space from the wall within the inner chamber to form an air space, whereby free circulation of air within the inner chamber is maximized. The receptacle is provided with a blowing fan for directing ambient air into the air inlet, whereby the inner chamber is connected with the ambient air and continuous air flow is permitted to circulate through the inner chamber to be exhausted through the through passage opening located in the lower portion.
Further, according to another aspect of the invention, a method is disclosed of keeping hot and for transporting prepared dishes from a producer to a consumer using a motor vehicle having a combustion engine, an exhaust supply tube in communication with the combustion engine for exhausting combustion exhaust fumes, and an exhaust tube. The method comprises equipping the motor vehicle with a container having a lower portion supported by the motor vehicle in which a heat exchanger is provided. The container comprises a receptacle having a continuous wall defining an inner chamber, and a door for permitting access to the inner chamber, the wall having a double wall portion enclosing a continuous air interspace. The double wall portion defines an air inlet to permit ambient air from the motor vehicle to be drawn into the air interspace, and, defines an air outlet connected to the inner chamber. The receptacle forms a through passage opening between the container and the motor vehicle thereby forming an air passage to ambient space and passing the exhaust supply tube and the exhaust tube through the through passage opening. The method further comprises connecting the heat exchanger between the exhaust supply tube and the exhaust tube within the inner chamber, whereby thermal energy from the exhaust fumes of the combustion engine of the motor vehicle supplies heat to the heat exchanger and permits conductive and radiational heat exchange through the heat exchanger into the inner chamber. In this manner, the inner chamber is connected with the ambient air and continuous air flow is permitted to circulate through the inner chamber to be exhausted through the through passage opening. The method further comprises delivering the dishes by placing the dishes in the container and operating the motor vehicle.
The forms of preferred embodiments of the invention will be described in more detail with their advantages in the following description with reference to the illustrations in t FIG.